United now uses Premier Qualifying Points (PQP) as their Status currency, you can mix them with Premier Qualifying Flights to determine status. As most other Spend you can optimize earnings with Star Alliance partners. Sadly, United implemented a cap on earnings per segment so not as lucrative as Delta with their SkyTeam partners.
All in One Chart:
The following purchases earn PQP:
Base fare + surcharge
Economy Plus® seating or subscriptions
Preferred seat purchases
MileagePlus Upgrade Award co-pays
Paid upgrades on flights operated by United and United Express
Flights ticketed and operated by our Star Alliance™ partners
Preferred partners include:
Air New Zealand
All Nippon Airways
Azul Brazilian Airlines
SWISS International Airlines
We will be adding more info on programs such as Aegean and Turkish soon...